Ti Powder Research Articles

Effect of Ti additive and preparation procedure on the temperature and decomposition kinetics of the MgH2 phase in the synthesized mechanicals alloys

The mechanical alloy Mg + 10 wt.% Ti and two mechanical alloys MgH2 + 10 wt.% Ti were synthesized by a reactive mechanical alloying (RMA) method, but in different ways. The influence of doping and the preparation procedure of mechanical alloys (MAs) on thehydrogen sorption properties, temperature and decomposition kinetics of their MgH2 phase was investigated by isobaric thermodesorption spectroscopy at a constant hydrogen pressure of 0.1 MPa. The desorption kinetics of the milled MgH2 + 10 wt.% Ti are faster than in the case of the ball milled Mg + 10 wt.% Ti. It was found that the manner of obtaining a mechanical alloys by reactive milling of MgH2 +10 wt. % Ti powder mixture rather than Mg +10 wt. % Ti powder mixture to improve the kinetic characteristics. The role of Ti as an alloying element in improving the hydrogen desorption kinetics of МAs obtained by various preparation procedures was studied. The stabilizing effect of Ti on the nanocrystalline structure and growth of the crystallites (grains) of the MgH2 phase during the cycling was also evaluated. It has been established the practical absence of the influence of Ti additive and the manner of obtaining MAs on the its thermodynamic stability.

Fabrication of Ti3Al-Based Intermetallic Alloy by Laser Powder Bed Fusion Using a Powder Mixture.

Due to their light weight and outstanding mechanical properties at high temperatures, Ti3Al-based intermetallic alloys have driven increasing interest from both academia and industry; however, when additive manufacturing (AM) is applied to them, the outcome is hardly satisfying. In this work, we report a crack-free Ti3Al-based alloy fabrication by laser powder bed fusion (LPBF) using a mixture of a commercial Ti-48Al-2Cr-2Nb powder and a pure Ti powder. With the aid of a high cooling rate during LPBF, the as-built sample shows a ductile β phase with some partially-melted particles. After the heat treatment, partially-melted particles were dissolved, and the sample showed equiaxed α2 precipitates in the β matrix. The hardness was 515 ± 38 HV in the as-built sample and 475 ± 37 HV in the heat-treated sample. This study shows a novel strategy to fabricate crack-free Ti3Al-based alloy using LPBF from powder blends.

Microstructure evolution and mechanical properties of in situ synthesized ceramic reinforced 316L/IN718 matrix composites

In situ synthesis of ceramic-reinforced 316L/IN718 matrix composites by directed energy deposition has been successfully achieved. The microstructure, microhardness, tensile properties and wear resistance of metal matrix composites were compared with those of unreinforced samples. The results show that there is good formability when the content of Ti powder is <20 %. With increasing Ti content, the microstructure morphology significantly changes, and the segregation size gradually increases. With the addition of Ti powder, the in situ synthesized Ti(C,N) and other hard particles during additive manufacturing enhanced the microhardness and wear resistance. 316L with 10 % Ti increased the microhardness to 629.6 HV and the ultimate tensile strength to 717.9 MPa, while decreasing the coefficient of friction to 0.688. This study provided a practical and cost-effective approach to prepare 316L/IN718-Ti composites as potential high-strength and wear-resistant materials.

Antibacterial Activity of Anatase TiO&lt;sub&gt;2&lt;/sub&gt; Added Cu Powder

To understand the mechanism of antibacterial activity of bulk Cu, N2-atomized Cu powder has been used instead. It was heated from 425 to 673 K in air for 4.2 • 102 s and measured by XRD and Chemi-luminescence (CL) to determine the contents of Cu2O and CuO, and reactive oxygen species (ROS), respectively; ROS being much affected by Cu2O and CuO can play a role to kill bacteria. Cu2O increased from 3.3 mass% (R.T.) to around 20% (673 K), however, CuO was almost constant (1.2~3.5%). High CL intensity was observed for Cu powders heated at 598~673 K. Then, a small amount of anatase TiO2 (a-TiO2) was added and heated at 673 K for 4.2 • 102 s in air, 1% O2-99% N2, and N2. The powder heated under 1% O2 showed the high CL intensity summation (∑CL), especially, 8.0 mol% a-TiO2 added and heated sample (“8.0Ti powder”) gave the about 4.7 times higher ∑CL than the starting material. ESR results using the spin-trap method showed that they contained hydroxyl radical •OH and its intensity increased from starting material to “8.0Ti powder”. However, bio-test proved that these samples revealed the same antibiotic activity. Formation mechanism of ROS (•OH and super oxide radical •O2-) on the surfaces of Cu/Cu2O/CuO has been proposed.

Development of low content Ti-x%wt. Mg alloys by mechanical milling plus hot isostatic pressing

Several authors have shown promising results using Ti and Mg to develop materials that combine the benefits of these two metals, such as their low density and absence of harmful second phases, which makes them attractive for aerospace and biomedical applications as well as for hydrogen storage. However, titanium and magnesium are almost immiscible and there are great differences in processing temperatures of these two metals. Within the techniques reported in the literature for obtaining Ti-Mg alloys, powder metallurgy and high-energy ball milling are possibly the most popular. In this work, Ti and Mg powders were mixed using a high-energy ball mill and subsequently these mixes were sintered by hot isostatic pressing (HIP), under various conditions, to obtain Ti-Mg alloys with Mg %wt. close to the limit of solubility (x < 2%wt.). The results showed the influence of the sintering parameters in the microstructure of the sintered material, which allowed us to obtain a Ti-Mg alloy instead of a composite material.

Towards strength-ductility synergy in nanosheets strengthened titanium matrix composites through laser power bed fusion of MXene/Ti composite powder

ABSTRACT A Ti3C2 MXene/Ti composite powder was developed through surface modification and powder coating for producing a high-performance titanium matrix composites (TMCs) by laser power bed fusion. Introducing MXene rarely changed the original sphericity and flowability of Ti powder while it slightly enhanced the laser absorption capacity of Ti powder. The printing conditions in turn affected the morphology and distribution of MXene in as-printed composites. At optimised printing parameters, majority of MXene with high structural integrity and uniform distribution remained along the grain boundaries of as-printed composites, and a combination of high surface quality, geometrical accuracy and densification was obtained. The remaining MXene played the synergy of pulling-out effect and load transfer role, which increased the yield strength from 530 to 710 MPa, while retaining good ductility (elongation of 19.8%). Compared with ASTM standard cast Ti64 alloy, our MXene/Ti composites also exhibited superior comprehensive tensile properties and excellent strength-ductility synergy.

Nature of the Increase in the Rate of Combustion of a Ti–C Mixture Diluted with an Inert Additive

An original comparative study is performed of the combustion of granular and powder Ti–C and (Ti–C)+20%Ni mixtures with granules of different sizes, while varying titanium particle sizes in a range of 31–142 mm. It is found that the rate of combustion of the (Ti–C)+20%Ni powder mixture is 2–3 times higher than that of a Ti–C mixture, despite the lower temperature of combustion of the former. The results are interpreted in terms of the convective–conductive combustion model and attributed to the inhibitory effect of impurity gases that evolve while heating the component particles ahead of the combustion front. The rate of combustion of the granules’ material is calculated using those of granular mixtures with granule sizes of 0.6–1.7 mm. This rate can be thought of as the rate of combustion of a powder mixture in which the effect of impurity gases is neutralized. It is proposed that the ratio of the rates of combustion of the material inside the granules and the powder mixtures be used as a quantitative measure of the effect impurity gas evolution has on the combustion of powder mixtures.

Cold Compaction Behavior of Unsaturated Titanium Hydride Powders: Validation of Two Compaction Equations

Unsaturated titanium hydride (TiHX) powder has high formability and is a promising raw material for titanium-based powder metallurgy. In this work, TiH2, TiHX, and HDH Ti powders were characterized, the cold compaction behavior of the powders was investigated, and the densification mechanism was analyzed. The TiHX was a three-phase mixture containing an α plastic phase and δ and ε brittle phases through Rietveld refinement. The TiHX compacts had compressive strength of over 420 MPa (higher than TiH2 and similar to HDHTi) and relative density of over 80% (higher than TiH2 and HDH Ti) at 600 MPa. The Gerdemann–Jablonski and Cooper–Eaton equation were used to simulate the powder compaction curves and describe powder compaction behavior. The plastic deformation of TiHX powder is greater than TiH2, and the particle rearrangement is greater than HDH Ti during cold compaction. Such compaction behavior of TiHX causes an excellent green-strength–relative-density combination.

Effect of Chlorine Salts on TiC Coating Morphology and Bonding Strength of Diamond Surface in Molten Salt Reaction

To obtain a high-quality TiC coating on the diamond (D) surface and improve the interfacial properties of metal matrix composites, the optimized molten salt method is used to prepare TiC coatings on the D surface. The effects of NaCl, KCl, and NaCl–KCl molten salts on the uniformity, surface morphology, composition, and bonding ability of TiC coatings are investigated by scanning electron microscopy, energy-dispersive X-ray spectroscopy (EDS), X-ray diffraction, and cold–hot cycling experiments. The results show that the boiling and pickling processes after the molten salt reaction can effectively remove the residual chloride salts and Ti powders to obtain clean TiC-coated D. The TiC particles of the coating surfaces prepared by NaCl and KCl molten salts are finer and more uniform, which is due to their higher melting points and shorter real reaction time compared with NaCl–KCl mixed salts. The TiC coating prepared by KCl has the best bonding ability and can withstand 50 times as many cold–hot cycles due to its uniform fine deposition particles and appropriate thickness. And, during cold–hot cycles, it can be found that the TiC coating cracking and shedding occur primarily at the edges and corners of the D with internal thermal stress concentration.

Metal injection molding of high-performance Ti composite using hydride-dehydride (HDH) powder

Aiming at solving the interstitial oxygen contamination for titanium (Ti) parts fabricated by metal injection molding (MIM) technology, we innovatively introduced LaB6 oxygen scavenger to eliminate its adverse effect and produce a high-performance Ti material using inexpensive hydride-dehydride (HDH) Ti powders. Rheological behavior of feedstocks, decomposition behavior of binders, as-sintered microstructure and mechanical properties were systematically studied. The viscosity of feedstock F2 containing LaB6 powder meets the requirement of injection molding operation. The as-sintered 0.5 wt% LaB6/Ti composite has homogenous and fine microstructure with the average grain size of 65.6 μm. The in-situ TiB and oxygen-containing (La2O3 and La-Cl-O) reinforcements are formed by the reaction of LaB6 and Ti matrix, which are uniformly distributed in the composite. The generated TiC particle and Ti matrix exist an orientation relation of (111¯)TiC||(011¯0)Ti and [101]TiC||[0001¯]Ti. The LaB6/Ti composite possesses excellent mechanical properties, with the ultimate tensile strength of 632 MPa, yield strength of 548 MPa and elongation of 15 %. Attributed to the oxygen scavenger of LaB6, the elongation of the composite is greatly increased by 163 % compared with pure Ti. This work provides a valuable guidance for the development of low-cost and high-performance Ti parts by MIM technology.

Microstructure evolution in compositionally graded Ti(4–12 wt% Mo) prepared by laser directed energy deposition

Compositionally graded Ti(4–12 wt% Mo) alloys were successfully prepared by laser directed energy deposition (L-DED) using two hoppers from Ti and Ti-15Mo master alloy powders. Detailed SEM, EDS and XRD analysis reveals the variation of the microstructure and consequently explains the evolution of the microhardness with the Mo concentration. High laser power is required to dissolve Ti-15Mo particles, to improve the homogeneity of the material at the scale of particle size, and to achieve a smooth linear gradient of the chemical composition. In the bottom part of the samples, the microstructure consists of elongated beta grains of the length of several mm containing big α-Ti laths. With increasing Mo concentration, the volume fraction of α phase decreases. Starting from the composition of about 9 wt% Mo the presence of ω phase was detected. Microhardness values span over a wide range of 270–550 HV and are affected by phase composition. The highest values of microhardness are achieved at around 10 wt% of Mo. However, phase composition and microhardness depend also on the utilized laser power and position in the sample determining the cooling rates. L-DED is capable of producing functionally graded materials (FGM) on the basis of metastable β-Ti alloys providing large variations of mechanical properties within a single sample/product.

Enhanced strength and ductility in a powder metallurgy Ti material by the oxygen scavenger of CaB6

• There exists a continuous oxide layer on the irregular HDH Ti powder surface. • CaB 6 addition promotes the improved sintered density and refines the grain size. • The scavenging of O by CaB 6 addition makes a high strength and superior ductility for α-Ti alloy. The challenge of producing a high-ductility titanium (Ti) material using inexpensive high-oxygen hydride-dehydride (HDH) Ti powder is hereby addressed by the incorporation of CaB 6 oxygen-scavenger. The oxygen-scavenging behaviour, microstructure evolution, mechanical behavior and improvement mechanism were systematically investigated. A continuous TiO 2 oxide layer with a thickness of approximately 9.3 nm is presented on the HDH Ti powder surface. The oxide layer will dissolve into Ti matrix during sintering, making the increase of c / a value and leading to the Ti-Ti bonds developing from plastic metal bonds toward brittle covalent bonds. The CaB 6 addition can scavenge O impurity and make a significant increase in tensile ductility for α-Ti matrix. A small addition of 0.2 wt.% CaB 6 provides a superior tensile elongation of 22.2% for Ti material, almost three times as high as that of pure Ti (7.5%). The increase of deformation twining activity and grain refinement are responsible for the improved ductility. Furthermore, the CaB 6 oxygen-scavenger can react with the surface oxide layer to in-situ form rod-like TiB and granular CaTiO 3 reinforcements, refining the coarse near equiaxed grain of α-Ti matrix into fine equiaxed crystals. The multiple mechanisms of grain-boundary strengthening, load-bearing strengthening of TiB and Orowan strengthening of CaTiO 3 nanoparticles work together to increase the tensile strength of Ti/CaB 6 composites. This work offers an effective method to fabricate high-performance Ti material using inexpensive high-oxygen HDH Ti powder.

SLA-Printed K-Band Waveguide Components Using Tollens Reaction Silver Plating

Dielectric printed and plated waveguide components offer cost and weight benefits over metal printed equivalents, with silver plating using Tollens reagents holding significant advantages over electroplating. This work extends on previous demonstrations of this process in plating stereolithography (SLA) printed resin waveguide parts by investigating number of plating rounds, reaction temperature and plastic base. It is found that less than 1.5 dB/m attenuation is achievable in WR42 waveguide using white SLA plastic and silver plating, comparing favourably with the 10 dB/m achieved by printing the same part using Ti64 powder bed fusion. This process improvement is further demonstrated using waveguide power dividers, slow-wave delay sections and rectangular horn antennas.

First principles study of Ti-Zr-Ta alloy phase stability and elastic properties

The effects of Ta and Zr content on the stability, elastic properties and electronic structure of Ti-Zr-Ta alloy phase were studied by first principles calculation method based on density functional theory. Moreover, Ti-Zr-Ta alloy was fabricated by spark plasma sintering (SPS) using spherical Ti powder,Ta powder, and Ti-Zr-Ta alloy powder produced by the plasma rotation electrode process (PREP). Afterward, the effects of sintering temperature, Zr and Ta content on the microstructure and mechanical properties of the alloy samples were investigated. The results showed that sintering temperature, Ta and Zr content were the key factors which affected the densification. When the sintering temperature was raised, the relative density and mechanical properties of Ti-Zr-Ta alloy were significantly increased. The first- principles calculation also indicated that Ti-1Zr-Ta possesses the lowest Young’s modulus and the best ductility, showing great potential of biomedical applications which agrees with the results of experimental results of alloy preparation.

Microstructure and Mechanical Properties of Core-Shell B4C-Reinforced Ti Matrix Composites.

Composite material uses ceramic reinforcement to add to the metal matrix to obtain higher material properties. Structural design is an important direction of composite research. The reinforcement distribution of the core-shell structure has the unique advantages of strong continuity and uniform stress distribution. In this paper, a method of preparing boron carbide (B4C)-coated titanium (Ti) powder particles by ball milling and preparing core-shell B4C-reinforced Ti matrix composites by Spark Plasma Sintering was proposed. It can be seen that B4C coated on the surface of the spherical Ti powder to form a shell structure, and B4C had a certain continuity. Through X-ray diffraction characterization, it was found that B4C reacted with Ti to form layered phases of titanium boride (TiB) and titanium carbide (TiC). The compressive strength of the composite reached 1529.1 MPa, while maintaining a compressive strain rate of 5%. At the same time, conductivity and thermal conductivity were also characterized. The preparation process of the core-shell structure composites proposed in this paper has high feasibility and universality, and it is expected to be applied to other ceramic reinforcements. This result provides a reference for the design, preparation and performance research of core-shell composite materials.

Plasma-sprayed Ti-Si-C coatings and their crystallization behaviors depending on Ti powder content

For plasma sprayed ceramic coatings, their crystallization behaviors are significantly different from conventional crystal solidification due to the rapid solidification rate, which would affect their mechanical properties. At present, there are few studies on the crystallization behaviors of the sprayed ceramic coatings. In this work, the Ti-Si-C ceramic coatings were reactive-plasma-sprayed using Ti/Si/graphite agglomerated powders with different Ti powder contents. Their crystallization behaviors and microhardness were investigated. The results demonstrated that the Ti-Si-C coatings mainly composed of TiC/Ti5Si3/Ti3SiC2 phases. With the increase of Ti contents, the Ti3SiC2 and Ti5Si3 phases decreased first and then increased, while the TiC phases content showed an opposite trend. As the Ti content increased, the columnar crystals were gradually perpendicular to the surface. The inner part of the lamellae composed of equiaxed crystals and columnar crystals, and the crystalline morphology of the coating cross-sections all displayed a lamellar columnar structure. The maximum microhardness of the coatings (HV 1201 ± 100) was obtained at a Ti/Si/graphite ratio of 3:1:2.

Microstructure and dynamic microhardness of additively manufactured (TiB2+TiC)/AlSi10Mg composites with AlSi10Mg and B4C coated Ti powder

In-situ synthesis of ceramics hybrid reinforced Al matrix composites (AMCs) by laser powder bed fusion (L-PBF) induced combustion reaction is a promising strategy to strengthen Al alloys. However, the in-situ formed microstructures are highly sensitive to the stability of mixed multi-powder feedstocks, which is a challenge to fabricate AMCs. This work develops a novel approach to obtain B4C coated Ti particles (hereafter as B4C@Ti) by collosol spraying to prepare (B4C@Ti)/AlSi10Mg composite powders. L-PBF technique was used to design and manufacture (TiB2+TiC)/AlSi10Mg composites by collosol coated powders. The effects of the coating process on the powder characteristics and phase structural evolution were systematically investigated, and the microstructures and dynamic microhardness of associated composites were monitored to reveal its underlying in-situ formation mechanism. Results indicate that the introduced B4C@Ti particles reduced the laser reflectivity of AlSi10Mg powders by 2.0 % and improved the K-M absorption factor by 4.8 %. The formation of Ti3SiC2 transition phase in the as-built composites was inhibited, and the supersaturated Si dissolution resulted in the lattice constant (a = 4.0466 Å) and interplanar spacing (d(111) = 2.3363 Å) of α-Al matrix phase increasing to 4.0504 Å and 2.3385 Å, respectively. The nanoscale TiB2 and TiC ceramic phases were in-situ formed within the elemental transition zone (ETZ) around the residual B4C particles, and the limited titanium source in the AlSi10Mg molten pool generated only TiB2 rather than TiB. The average values of dynamic microhardness of the L-PBF as-built composites concomitantly increased from 1.37 ± 0.08 GPa to 1.80 ± 0.13 GPa.

Effect of Mo ratio on the microstructure and mechanical properties of TiMoNi alloys fabricated by powder metallurgy method

TiNi alloys have good biocompatibility and are widely used as biomaterials in the human body. Mo is a nontoxic element and increases biocompatibility as well as corrosion resistance. Ti-Mo-Ni-based alloys utilized in biomedical applications should have high strength. In this context, the microstructure and mechanical properties of TixMo6Ni alloys produced by the powder metallurgy method were investigated in this study. Five different Ti alloys were obtained by adding a fixed amount of (6%) Ni and different ratios (1, 3, 5, 8, 10%) Mo into the Ti powder. Alloy powders were sintered at different temperatures after pressing with a constant pressure of 520 MPa. In general, the highest density values were reached at 1250 °C. Microstructure examinations were performed by scanning electron microscopy (SEM), energy distribution spectrometry (EDS) and X-ray diffraction analysis (XRD) analyses. In the microstructure, it was observed that the grain size and pores increased as the Mo ratio increased. The hardness values increased with the increase of the Mo ratio. However, the relative density values decreased with increasing Mo ratio.

Improved mechanical properties of steel/aluminum laser welding joint by Ti powder addition: experimental and first-principles investigations

Improved mechanical properties of steel/aluminum laser welding joint by Ti powder addition: experimental and first-principles investigations

Laser Cladding Treatment to Enhance the Corrosin Resistance and Surface Hardness by Electrophoretic Coatings to A283 Steel

Laser cladding (LC) is a laser-based surface modification technology that has been widely adopted for the development of thin layers that operate under harsh conditions. Corrosion contributes to approximately 50% of oil and refinery equipment failures. These major risks require sophisticated methods to improve oil equipment performance. LC promotes the generation of superior properties on the substrate surface, which improves service life. To reduce corrosion failure and enhance life cycles, we conducted electrophoretic deposition (EPD) of Ti and Ni powders and directly coated them on A283 steel alloy, which was alloyed by ND-YAG LC and the remelted surface of A283 steel alloy. The microstructure, element distribution and phase analysis of the cladding sample were studied by optical microscopy, field-emission scanning electron microscopy, X-ray energy-dispersive spectrometry, atomic force microscopy and X-ray diffraction methods. The results indicated that the coatings with fine metallurgical bonding to the substrate comprised major stable FeTi and FeNi and illustrated two different regions of solidification microstructures. The LC process and powder feeding by EPD were applied, which improved the mechanical properties, corrosion behaviour, phase transformation and structural optimisation of the surface microstructure of the laser mixed zone. Melting of the coated sample showed that the coating produced by laser treatment had a smooth top surface. In addition, we have a proven case of surface treatment with a laser that delivered the required performance. Moreover, this treatment is a more environmentally friendly alternative to traditional surface preparation treatments.